Conventionally, an image projection apparatus as typified by a projector is designed to project video images output by a computer, media player, or the like for viewing purposes, and is used not only in conference rooms and stores, of course, but also in homes.
The conventional projector, because it is designed to project onto a large screen, is relatively large itself, and is usually affixed to the ceiling or placed on a desk or the floor when in use.
Operation of this type of projector is typically carried out using a variety of buttons provided on the body of the projector or with a remote-control device provided as an accessory to the projector.
By contrast, in order to view images in small groups of four or five people, equipping a mobile phone with a built-in, small-scale image projection apparatus has been proposed (see Japanese Patent Application Publication No. 2005-236746).
When projecting video images using an image projection apparatus built into a mobile phone, it is contemplated that the mobile phone is taken and held in the hand. Then, it is assumed that a need arises to operate the image projection apparatus during projection, for example, to switch images, or to change the settings of the image projection apparatus.
In this case, it is likely that operation is carried out using the phone buttons and keys with which mobile phones are ordinarily provided. However, operating buttons and keys while holding the mobile phone and projecting images causes the projection place to fluctuate and the size of the projected images to fluctuate, and is not easy to use.
Moreover, providing the mobile phone with a separate remote-control device for operating the image projection apparatus is not practical.
Thus, conventionally, there has been no proposal to facilitate user operations taking into account a case in which the image projection apparatus has been made so compact that it is held in the hand when used.